Southern41™ Thermal is a leading thermally broken joinery system, offering a wide range of window and door products to suit various design requirements.
The Southern41™ System is a pioneer in the world of residential joinery systems. With its efficient thermally broken aluminium design, the system is central to maintaining a comfortable temperature throughout your home all year round. Say goodbye to chilly winters and sweltering summers - Southern41™ reduces thermal transference, saving you energy and money.
Compatible product types include:
- Ranchslider®, with LevelStep™ Sill upgrade option
- Euroslider™
- Hinged and Bifold doors
- Fixed, awning and casement windows
Designed with a 41mm platform, the system accommodates double glazing with Low-E coated glass. Whether you're building new, looking to upgrade your windows or revamp your doors, the Southern41™ System has you covered.
Thermal Break overview
A thermal break in aluminium windows and doors is an insulating barrier placed between the interior and exterior sections of the frame. It prevents heat and cold from transferring through highly conductive aluminium – reducing energy loss and improving thermal performance. The result is a more energy efficient and comfortable home, reduced condensation, and an environment that makes it easier to maintain your home at an optimal ‘healthy home’ minimum temperature of 18º Celsius year-round.
Southern41™ thermally broken joinery is engineered using the advanced ‘Pour and Debridge’ method. This process involves filling a specially designed channel in the aluminium frame with a high-performance resin (‘Pour’). The back of the channel is then milled out (‘Debridge’), severing the direct connection between the inner and outer frame and creating a 5mm thermal break.
Core performance aspects

Performance up to and exceeding Extra High wind zone rating. *2.4m high is recommended. Larger spans may be possible. Please contact your local Fisher® Windows consultant for more information.

The Southern41™ frame combines sleek, modern lines with refined detailing to create a sophisticated, high-end aesthetic. Elevates residential spaces with effortless elegance. The Kleenline™ infill can be added to further enhance your window and door experience.

Designed and manufactured right here in New Zealand to suit our local conditions. With decades of proven performance, our products are backed by industry-leading warranties and the assurance that we’ll be here to support you – providing reliability and peace of mind long after installation.

Fisher® Windows Windows and Doors comply with the New Zealand Standards NZS4211:2008 Specification for Performance of Windows and NZS3504:1979 Specification for Aluminium Windows. Fisher® Windows is also a member of the Window and Glass Association of New Zealand.

Southern41™ is fully stocked in New Zealand’s Top 6 trending colours. We also offer a key range of 36 colours, plus more on request. With finishes in matte, gloss, pearlescent and textures, we’ve got the look you’re after.